Leg Heating in Pregnant Women With Obesity

NCT06932250 | Recruiting DMC

• 1 other identifier: STU20250500
• Study Type: interventional
• Target: 118
• Locations: 1 country
• Sites: 1

Brief Summary

Obesity is a major risk factor for hypertensive disorders of pregnancy (HDP). The underlying mechanisms are largely unclear, but maternal vascular endothelial dysfunction is likely involved. Endothelial dysfunction in HDP could be attributed to 1) alterations in the L-arginine/nitric oxide (NO) pathway, and 2) an increase in endothelin-1 (ET-1). Additionally, augmented sympathetic vasoconstriction may also contribute to HDP. Chronic (repeated) whole-body heat exposure has been shown to increase NO bioavailability, decrease ET-1, and cause functional and structural adaptations in the vasculature. All these can improve vascular function, attenuate sympathetic (re)activity, lower blood pressure (BP), and reduce cardiovascular risk in non-pregnant individuals. Whether this is also true after regional (leg) heating in high-risk pregnant women is unknown. The investigators' central hypothesis is that chronic leg heating will be effective in improving vascular endothelial function and attenuating sympathetic vasoconstriction, leading to a reduction of the risk for HDP in pregnant women with obesity. The overarching goal of this proposal is to determine the vascular and neural effects of chronic leg heating in obese pregnancy. The study team plans to enroll pregnant women with obesity between 12-14 weeks of gestation and randomly assign them to either an intervention group or a control group (1:1 ratio). Participants in the intervention group will perform 16 weeks of home-based leg heating using a portable sauna blanket up to the hip (temperature of the blanket will be set at 65°C, 4 times/week, 45 min/session), whereas women in the control group will set the temperature of the blanket at 35°C at the same frequency and duration. Participants will be evaluated at baseline and then at 28-30 weeks of gestation. Aim 1 will determine the effects of chronic leg heating on maternal vascular function and surrogate markers of HDP. Aim 2 will determine the effects of chronic leg heating on sympathetic vasoconstriction and BP. Findings from this project will provide insight on the extent and potential mechanisms of how chronic leg heating works for improving vascular endothelial function and sympathetic vasoconstriction in pregnant women with obesity. Results obtained will set a foundation for future large multicenter clinical trials to determine the efficacy and generalizability of home-based leg heat therapy as a safe, ease-of-use, cost-effective, and non-drug approach for reducing the risk of HDP.

Conditions

High-risk Pregnancy

Keywords

Pregnancy; Obesity; Heat therapy; Vascular function; Sympathetic neural control; Blood pressure

Outcome Measures

Primary Outcomes (3)

• Change in vascular endothelial function

  Change in vascular endothelial function assessed by brachial artery flow-mediated vasodilation using the Doppler ultrasound technique

  Baseline, 16 weeks after leg heating

• Change in sympathetic neural control

  Change in sympathetic neural control assessed by muscle sympathetic nerve (re)activity using the microneurographic technique

  Baseline, 16 weeks after leg heating

• Change in sympathetic vascular transduction

  Change in sympathetic vascular transduction assessed using the microneurographic and Doppler ultrasound techniques

  Baseline, 16 weeks after leg heating

Secondary Outcomes (10)

• Change in blood concentration of nitrate

  Baseline, 16 weeks after leg heating

• Change in blood concentration of nitrite

  Baseline, 16 weeks after leg heating

• Change in L-arginine level

  Baseline, 16 weeks after leg heating

• Change in asymmetric dimethylarginine level

  Baseline, 16 weeks after leg heating

• Change in 3-nitrotyrosine level

  Baseline, 16 weeks after leg heating

Study Arms (2)

Sauna blanket set at 65°C

EXPERIMENTAL

The temperature of the sauna blanket will be set at 65°C and participants will perform home-based leg heating 4 times per week, 45 minutes per session.

Other: Leg heating

Sauna blanket set at 35°C

PLACEBO COMPARATOR

The temperature of the sauna blanket will be set at 35°C and participants will perform home-based leg heating 4 times per week, 45 minutes per session.

Other: Leg heating

Interventions

Leg heating OTHER

Participants will perform home-based leg heating using a portable sauna blanket set at different temperature.

Sauna blanket set at 35°C; Sauna blanket set at 65°C

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Women with overweight or obesity (self-reported pre-pregnancy body mass index ≥25 kg/m2) between 10-14 weeks of gestation and aged 18-45 years old will be enrolled.
• Both normotensive and hypertensive (office sitting systolic BP 140-150 mmHg and/or diastolic BP 90-100 mmHg) pregnant women will be enrolled if they are not on any antihypertensive drug treatment.
• We will enroll both nulliparous and multiparous women.
• There is no restriction regarding race/ethnicity and socioeconomic status.
• Women with a history of HDP will be allowed to participate.
• Women taking low-dose aspirin will be allowed to participate and aspirin use will be documented.

You may not qualify if:

• Current multiple pregnancies (e.g., twins, triplets, etc.).
• Known major fetal chromosomal or anatomical abnormalities diagnosed during the study.
• Recurrent miscarriage (three or more, to avoid antiphospholipid antibody syndrome).
• Office sitting BP \<100/55 mmHg or \>150/100 mmHg (for safety reasons).
• Evidence of cardiovascular, pulmonary, or neurological diseases.
• Diabetes mellitus (to avoid its effects on vascular endothelial function and sympathetic vasoconstriction).
• Kidney disease (serum creatinine \>0.9 mg/dL).
• Clinical known deep vein thrombosis, clinical symptoms and history of deep vein thrombosis, or dermatological lesions.
• History of drug or alcohol abuse within the last 2 years.
• Current tobacco use.
• Pregnant women who do not have air conditioning at home during summer (for safety reasons).

Sponsors & Collaborators

• University of Texas Southwestern Medical Center: lead

Study Sites (1)

UT Southwestern Medical Center; Institute for Exercise and Environmental Medicine

Dallas, Texas, 75231, United States

RECRUITING

Related Publications (40)

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MeSH Terms

Conditions

Obesity; Hyperthermia

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Body Temperature Changes; Heat Stress Disorders; Wounds and Injuries

Study Officials

• Qi Fu, MD, PhD

  UT Southwestern Medical Center; Institute for Exercise and Environmental Medicine

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Qi Fu, MD, PhD

CONTACT

214-345-8125; QiFu@TexasHealth.org

Monique Roberts-Reeves, RN

CONTACT

214-345-4656; MoniqueRoberts-Reeves@TexasHealth.org

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: March 19, 2025
• First Posted: April 17, 2025
• Study Start: August 1, 2025
• Primary Completion (Estimated): January 31, 2030
• Study Completion (Estimated): April 30, 2030
• Last Updated: April 17, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR, ANALYTIC CODE
• Time Frame: After the manuscripts are published.

Locations

US (1)